Iowa Counties by Population (2026)
2026 Pop.
50K
100K
150K
200K
250K
300K
350K
400K
450K
500K
Top 5 Most Populous Counties
533,581
236,482
177,625
163,836
134,686
99 Counties
| County | 2026 Pop. ↓ | Area (mi²) | Density | Change (2020) |
|---|---|---|---|---|
| Polk County | 533,581 | 572 | 933 | 8.22% |
| Linn County | 236,482 | 717 | 330 | 2.63% |
| Scott County | 177,625 | 458 | 388 | 1.72% |
| Johnson County | 163,836 | 613 | 267 | 7.05% |
| Black Hawk County | 134,686 | 566 | 238 | 2.78% |
| Dallas County | 122,843 | 588 | 209 | 22.18% |
| Woodbury County | 108,683 | 873 | 124 | 2.58% |
| Story County | 104,492 | 573 | 182 | 5.92% |
| Dubuque County | 99,750 | 608 | 164 | 0.44% |
| Pottawattamie County | 93,881 | 951 | 99 | 0.24% |
| Warren County | 58,433 | 570 | 103 | 11.11% |
| Clinton County | 45,777 | 695 | 66 | -1.41% |
| Cerro Gordo County | 42,539 | 568 | 75 | -1.12% |
| Muscatine County | 41,764 | 437 | 96 | -3.22% |
| Marshall County | 40,716 | 573 | 71 | 1.56% |
| Des Moines County | 38,513 | 416 | 93 | -0.88% |
| Jasper County | 38,339 | 730 | 53 | 1.38% |
| Webster County | 37,421 | 716 | 52 | 1.16% |
| Sioux County | 36,864 | 768 | 48 | 2.69% |
| Wapello County | 36,209 | 432 | 84 | 2.5% |
| Marion County | 34,708 | 554 | 63 | 3.87% |
| Lee County | 32,110 | 518 | 62 | -4.23% |
| Boone County | 27,053 | 570 | 47 | 1.31% |
| Plymouth County | 25,945 | 863 | 30 | 0.98% |
| Benton County | 25,859 | 716 | 36 | 1.21% |
| Bremer County | 25,376 | 435 | 58 | 1.48% |
| Washington County | 22,785 | 569 | 40 | 1.08% |
| Mahaska County | 22,168 | 571 | 39 | 0.03% |
| Jones County | 21,514 | 576 | 37 | 4.16% |
| Buena Vista County | 21,052 | 575 | 37 | 1.17% |
| Buchanan County | 20,749 | 571 | 36 | 0.69% |
| Carroll County | 20,197 | 569 | 35 | -2.59% |
| Winneshiek County | 19,713 | 690 | 29 | -1.69% |
| Jackson County | 19,464 | 636 | 31 | 0.06% |
| Fayette County | 18,978 | 731 | 26 | -2.42% |
| Henry County | 18,937 | 434 | 44 | -7.38% |
| Poweshiek County | 18,368 | 585 | 31 | -1.4% |
| Dickinson County | 18,300 | 381 | 48 | 2.97% |
| Cedar County | 18,155 | 579 | 31 | -1.77% |
| Delaware County | 17,661 | 578 | 31 | 1.19% |
| Madison County | 17,485 | 561 | 31 | 5.15% |
| Crawford County | 16,858 | 714 | 24 | 2.22% |
| Clayton County | 16,823 | 778 | 22 | -1.24% |
| Tama County | 16,640 | 721 | 23 | -2.37% |
| Iowa County | 16,497 | 586 | 28 | -0.94% |
| Clay County | 16,362 | 567 | 29 | 0.15% |
| Hardin County | 16,346 | 569 | 29 | -2.85% |
| Jefferson County | 16,091 | 436 | 37 | 2.5% |
| Page County | 15,090 | 535 | 28 | -0.72% |
| Hamilton County | 14,872 | 577 | 26 | -0.93% |
| Mills County | 14,867 | 437 | 34 | 3.11% |
| O'Brien County | 14,646 | 573 | 26 | 3.51% |
| Harrison County | 14,602 | 697 | 21 | 0.24% |
| Floyd County | 14,492 | 501 | 29 | -7.06% |
| Kossuth County | 14,404 | 973 | 15 | -2.62% |
| Allamakee County | 14,216 | 639 | 22 | 1.04% |
| Butler County | 14,018 | 580 | 24 | -2.2% |
| Cass County | 12,810 | 564 | 23 | -2.33% |
| Wright County | 12,699 | 580 | 22 | -1.73% |
| Lyon County | 12,558 | 588 | 21 | 5.33% |
| Grundy County | 12,391 | 502 | 25 | 0.36% |
| Appanoose County | 12,060 | 497 | 24 | -1.82% |
| Union County | 12,039 | 424 | 28 | -0.73% |
| Shelby County | 11,817 | 591 | 20 | 0.77% |
| Chickasaw County | 11,769 | 504 | 23 | -1.8% |
| Cherokee County | 11,670 | 577 | 20 | 0.1% |
| Louisa County | 10,810 | 402 | 27 | -0.14% |
| Mitchell County | 10,808 | 469 | 23 | 2.1% |
| Guthrie County | 10,796 | 591 | 18 | 1.67% |
| Hancock County | 10,586 | 571 | 19 | -1.6% |
| Franklin County | 10,282 | 582 | 18 | 2.87% |
| Winnebago County | 10,023 | 400 | 25 | -5.94% |
| Montgomery County | 9,893 | 424 | 23 | -4.23% |
| Humboldt County | 9,723 | 434 | 22 | 1.31% |
| Keokuk County | 9,671 | 579 | 17 | -3.41% |
| Calhoun County | 9,553 | 570 | 17 | -3.46% |
| Howard County | 9,366 | 473 | 20 | -1.38% |
| Clarke County | 9,310 | 431 | 22 | -4.32% |
| Sac County | 9,273 | 575 | 16 | -5.38% |
| Davis County | 9,249 | 502 | 18 | 1.47% |
| Emmet County | 8,932 | 396 | 23 | -4.39% |
| Palo Alto County | 8,813 | 564 | 16 | -2% |
| Greene County | 8,792 | 570 | 15 | 0.48% |
| Lucas County | 8,724 | 431 | 20 | 1.21% |
| Monona County | 8,281 | 694 | 12 | -5.27% |
| Adair County | 7,495 | 569 | 13 | 0.08% |
| Decatur County | 7,406 | 532 | 14 | -4.23% |
| Worth County | 7,277 | 400 | 18 | -2.06% |
| Monroe County | 7,147 | 434 | 16 | -5.91% |
| Van Buren County | 7,119 | 485 | 15 | -1.37% |
| Pocahontas County | 6,970 | 577 | 12 | -1.39% |
| Wayne County | 6,782 | 525 | 13 | 4.31% |
| Ida County | 6,760 | 432 | 16 | -3.83% |
| Fremont County | 6,566 | 511 | 13 | -0.02% |
| Osceola County | 6,076 | 399 | 15 | -2% |
| Taylor County | 5,641 | 532 | 11 | -3.75% |
| Audubon County | 5,620 | 443 | 13 | -1.06% |
| Ringgold County | 4,532 | 535 | 8 | -2.39% |
| Adams County | 3,712 | 423 | 9 | 0.05% |
Overview of Iowa Counties
There are 99 counties in Iowa.
Polk County is the largest county in the state, with a population of 533,581. The most recent census shows that its population has increased by 0.08% since the previous census.
A number of other Iowa counties also boast relatively large populations for their state, though not able to match the density of Polk County:
- Linn County : 236,482
- Scott County : 177,625
Iowa Counties with the Fewest Residents
The smallest county in Iowa is Adams County , with a population of just 3,712. This total represents a increase of 0.0% since the last census count was performed.
Other small counties include:
- Ringgold County : 4,532
- Audubon County : 5,620
- Taylor County : 5,641
Iowa Counties with Rapid Growth
Dallas County , with its sizeable population of 122,843, has shown the largest population growth, with an increase of 0.2% since the last census.
Polk County has also had relatively high population growth of 0.08% with 533,581 residents.
On the other hand, Henry County has had the largest decrease in population, with its 18,937 current residents totalling 0.1% less than the previous census.
Sources
- US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
- US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
- American Community Survey (2009 - 2013)
- Census QuickFacts
- Historical Populations of States and Counties (1790 - 1990)